Percussion fuse



Oct. 26, 1937.

M. BIRKIGT PERCUSS ION FUSE Filed March 27, 1936 2 Sheets-Sheet l a me ATTORNE Oct. 26, 1937. M.l BIRKIGT 2,097,015

PERCUSS ION FUSE Filed March 27, 1936 2 Sheets-Sheet 2 .Q3 E *D 1 w Q l N 'f w iff-fi? N w@ im N h t N N H w' Q Y Mw Patented Oct. 26, 1937 UNETED STATES PATENT GFFHQE vApplicatiim March 27, 1936, serial Ne. 71,326

In Belgium January 17, 1936 6 Claims.

The present invention relates to percussion fuses for projectiles rotating about their axis along their trajectory and it concerns, especially although not exclusively, fuses for small caliber shells.

The object of the present invention is to provide a fuse of this type which is better adapted to meet the requirements of practice than fuses for the same purpose made up to the present time.

According to the present invention, I make use of balls or the like for locking the striker or ring pin as long as it is necessary, that is during handling of the projectile and before it is red from the gun, and I devise the parts in such manner that, when the projectile is rotating about its axis, these locking balls are slidably held for a certain length of time between two parts which move relative to each other, while the balls move away from the axis of revolution of the projectile, for releasing the striker or firing pin.

Other features of the present invention will result from the following detailed description of specific embodiments thereof.

Preferred embodiments of the present invention will be hereinafter described, with reference to the accompanying drawings, given merely by way of example, and in which:

Fig. 1 is an axial sectional view of a percussion fuse made according to a first embodiment of the present invention;

Figs. 2, 3 and 4 are views, similar to Fig. 1, illustrating different characteristic positions of the parts of the fuse, in the course of the operation thereof;

Fig. 5 is an end View of one of the elements of said fuse;

Fig. 6 is a partial sectional view, similar to Fig. 1, showing a modification; l

Fig. '7 is an axial sectional view of a percussiony fuse made according to another embodiment of the present invention;

Figs. 8, 9, and 10, similar to Fig. '7, illustrate different characteristic positions of the parts of the fuse shown in said Fig. 7, corresponding to diiferent characteristic relative positions of the parts of said fuse in the course of the operation thereof;

The embodiments described by way vof example describe percussion fuses for projectiles to be iired in guns provided with riilings.

In order to lock the ring pin which is carried by the fuse, as long as necessary to obtain a safety period, I provide `a system of balls capable, as long as they are kept close to the center line of the fuse, to bear rearwardly against a xed stop element and to form stops for an enlarged portion of the firing pin or striker, so as to prevent the latter from coming into contact 5 with the detonator of the fuse.

4The fuse body consists of a hollow metallic piece l which extends rearwardly, in the usual manner, so as to form a chamber 2 containing detonator 3 and priming charge This cham- 10 ber is ciosed by a fixed piece 5 in the central part of which there is provided a hole through which the firing pin l is slidably guided.

The front part of said body l is then hollowed out in such manner as to form therein a chamber 8 having, at the front part thereof, an axial bore closed at its front end by a small disc lil.

Firing pin or striker 1 includes, on the one hand, a head li capable of sliding in bore 9, and on the other hand an enlarged part i2, 2O located for instance at the middle part of said firing pin, this enlarged part being adapted to form the front stop for the locking balls I3.

I further provide, in chamber 2, an element capable of acting as a rear stop for said balls, 25 said element consisting, for instance, of 'a cylindrical sleeve l carried by piece 5.

The fuse body being thus constituted, I provide means whereby balls I3 are held between two parts which move away from each other when the projectile is rotating after being red, while the balls themselves move away from the axis of rotation under the effect of the centrifugal force, so as to release the striker or ring pin by moving out of the way of said enlarged portion of the ring pin.

Such, an arrangement may be made in different manners but the embodiment shown by the `drawings is believed to be the most advantageous.

As shown by way of example vby Figs. 1 to 4, 40 there is provided in chamber S, behind bore 9, a longitudinal housing i5, for instance of cylindrical shape, which may extend rearwardly as far as Vsleeve |45.

Inside this housing 15a ring-shaped member I6 is securely, but elastically, held in said housing. For instance, as shown by the drawings (Fig. 5) this ring-shaped member i6 is slit and given a size such that it must be contracted for inserting it into housing i5, so that ring-shaped member 1S is securely held in position by friction as long as it is not subjected to the action of an extremely high force, such as that exerted thereon, in a rearward directiomwhen `the cartridge is recl.

This ring-shaped member I 6 is made of such a height and a thickness such that, on the one hand, when it occupies its front position (Fig. l), in which it is set when the parts are assembled, its rear end is located opposite balls I3 when the latter are located between sleeve I4 and the enlarged part I2 of the firing pin, thus keeping said balls in the locking position. On the other hand, when said member I8 is in its rear position (Figs. 2 to 4), which occupies after the cartridge has been fired, the front part of said member I6 is located opposite balls I3.

The inner face of this front part of member I6 is of flaring shape toward the front, forming a cone of an angle of for example said conically-shaped part being advantageously of a length such that, when ring-shaped Vmember I6 is in its rear position, balls I3 are located opposite said conical part of member I6.

The ring pin and its enlarged part I2 are arranged in such manner that, when, under the effect of the centrifugal force, balls I3 move forward into said conical portion I'I, they push said ring pin gradually toward the front until they are capable of moving past enlarged portion I2, thus releasing the firing pin.

For this purpose, for instance, the rear face of the enlarged part I2 of said ring pin is given the shape of a cone I8 the apical angle of which is greater than that of conical part I'I, for instance Supposing now that all the parts of the fuse above described are assembled as shown by Fig. l, in which the striker or ring pin is locked, this fuse works in the following manner:

When the shot is fired, ring-shaped member I6 is moved rearwardly (Fig. 2), the enormous acceleration of the shell in the bore of the gun keeping the balls applied against sleeve I4 and the firing pin applied against the balls.

When the acceleration ceases, that is to say after the shell has left the gun, the balls are gradually caused to rotate,rrolling at a higher and higher rate inside part I'I and pushing firing pin Il forwardly.

Finally, said firing pin is released when the balls have moved past the edge of enlarged portion I2.

It will, be readily understood that the safety period elapsing after the shell has left the gun depends upon the time during which the firing pin is moving forwardly under the effect of the thrust of the balls and also upon the retardation of the movement of the shell along its path of travel.

In order to obtain this period of any desired length, I may, for instance, provide balls of a size and weight depending on the length of such period. The apical angles, the axial length and relative thickness of conical portions II and I8 may also be made of various sizes to affect the length of the safety periods.

I may also, in order to increase safety, provide means for retarding the forward movement of the striker .or firing pin. l

For instance I could arrange the head I I of the striker or ring pin and bore 9 as an air brake or dash-pot.

I may also provide for a certain friction between head I I and bore 9, for instance by means of an elastic annular member I9 (Fig. 6) carried by the front part of said head and adapted to slide frictionally along the wall of said bore.

I may also, still for the same purpose, vary the size and Weight of the striker, for example, for

increasing or reducing the friction between pin 'I and the wall of hole 6.

Advantageously, according to the present invention, said striker is made of two parts, that is, a steel body carrying the portion I2 of enlarged section and a head portion of light metal, for instance fixed to said body through securing means 2G which can be opened if, for some accidental reason, the head of the firing pin undergoes a shock during handling.

For this purpose, the front face of enlarged portion I2 is made of frusto-conical shape and it carries a projection 2I the base of which is provided with a groove in which is fixed the base of a tubular element of relatively small thickness which carries head II.

According to another embodiment of the invention, illustrated by Figs. l'l to 10, the fuse is similar to that' above described but, instead of a single ring-shaped element I6 it includes two ring-shaped members 22 and 23. Element 22, located at the rear part of the device is fitted with considerable friction inside housing I5 and it serves to lock the parts in inoperative position. The other ring-shaped member 23 is adapted to slide freely inside said housing and serves to keep the balls in locking position after the shot has been red until the projectile reaches the desired point of its trajectory.

This type of fuse was described in applicants prior patents.

Ring-shaped member 23 is provided, at the rear part thereof, with a bevel 2 arranged in such manner that its forward edge is located opposite the balls when, after the shot has been red, ring-shaped members 22 and 23 have moved simultaneously in a rearward direction. This position is shown by Fig. 8.

While in prior devices, the forward movement of ring-shaped member 23 took place only as a result of the retardation of the motion of the projectile along its trajectory, in the present fuse, this movement is further increased by the thrust of the balls on bevel-shaped part 2Q, as said balls are being gradually placed in rotation by the body of the fuse.

Anyway, when ring-shaped member 23 has been pushed in a forward direction a sufficient distance, balls I3 engage between the two ringshaped members (Fig. 9) and release the striker so that the latter, when the projectile meets an obstacle, is free to strike the detonator (Fig. 10)

In the general manner, While I have, in the above description, disclosed what I deem to be practical and eiiicient embodiments of the present invention, it should be well understood that I do not wish to be limited thereto as there might be changes made in the arrangement, disposition and form of the parts without departing from the principle of the present invention as contained within the scope of the appended claims.

What I claim is:

1. A fuse for a projectile intended to move along its trajectory with a rotary movement about said trajectory which comprises, in combination, a fuse body, a detonator carried by said body, an axial striker movable in said body for action on' said detonator, balls adapted to coact with said striker for locking it in a position out of contact with'said detonator, means for keeping said balls in the locking position thereof, adap-ted to be brought out of action by the acceleration undergone by the projectile when the latter is fired, and a member movable axially in said body having a flaring surface adapted to cooperate with said balls so as to permit outward motion thereof for releasing them from locking engagement with said striker when said member is moved axially by the axial component of the thrust exerted, under the eiect of the centrifugal force, by said balls on said member.

2. A fuse for a projectile intended to move along its trajectory with a movement of rotation about said trajectory which comprises, in combination, a fuse body with a cylindrical axial housing therein, a detonator carried by said body, a striker movable axially in said housing for action on said detonator, balls in said housing adapted to operatively engage said striker for locking it in a position out of contact with said detonator, a ring fitting with a high friction in said housing, the rear part of the inner surface of said ring being of cylindrical shape so as to normally keep said balls into engagement with said striker and the fro-nt part of said inner surface being of frontwardly aring shape, said ring being adapted to slide in said housing, under the effect of the acceleration undergone by said projectile when the shot is fired, into a position in which said :Haring surface cooperates with said balls, and a conical part rigid with said striker adapted to cooperate with said balls so as to transmit to the striker a frontward movement under the effect of the axial component of the thrust exerted thereon, under the effect of the centrifugal force, by said balls running along said flaring inner surface of said ring, whereby said conical part is brought into a position in which it permits said balls to escape outwardly into the peripheral part of said housing, between said conical part and the front edge of said ring.

3. A fuse according to claim 1 in which the means for keeping said balls in the locking position prior to the firing of the shot consist of a ring fitting with a high friction inside said body, and the member movable in said body consists of a ring having a bevelled inner surface movable freely inside said body.

4. A fuse for a projectile intended to move along its trajectory with a rotary movement around its axis, comprising in combination a fuse body, a detonator and a striker within said body, said striker and said detonator being movable relative to each other for bringing said striker in contact with said detonator, means for normally preventing said movement, said means being movable within said fuse body toward the outside under the action of centrifugal force when said projectile is rotating about its own axis, annular means surrounding said first means, said last means having at least one cylindrical and one conical inner wall and being movable axially within said fuse body, said last means being so positioned relative to said rst means that said cylindrical wall is located opposite said first means before said projectile is fired, while said last means are moved by the inertia of ring into a position where said first means are surrounded by said conical wall, whereby said rst means are disengaged from locking position in which said relative movement was prevented by the centrifugal action of said rst means upon said conical wall.

5. A fuse for a projectile according to claim 4, said annular means being frictionally secured in position and in contact with said first means before said projectile is fired.

6. A fuse for a projectile intended to move along its trajectory with a rotary movement around its axis, comprising in combination a fuse body, a detonator and a striker within said body, said striker and said detonator being movable relative to each other for bringing said striker in contact with said detonator, means for normally preventing said movement, said means being movable within said fuse body toward the outside under the action of centrifugal force when said projectile is rotating about its own axis, a support having a conical inner Wall and being movable axially within said fuse body, means for holding said first means in the locking position thereof and said support out of contact with said first means before said projectile is fired, while said last means are moved by the inertia of firing into a position where said rst means are surrounded by said conical wall, whereby said rst means are disengaged from locking position in which said relative movement was prevented, by the centrifugal action of said rst means upon said conical wall.

MARC BIRKIG'T. 

